Combustion turbines benefit substantially from chilling the inlet air on warm days. Both capacity and efficiency improve. The improvements are maximized by using turbine waste heat to supply the chilling, in lieu of mechanical power. Examples of this are found in U.S. Pat. Nos. 6,739,119; 6,457,315; and 5,782,093.
As the inlet air accelerates in the bellmouth, it experiences adiabatic cooling. At inlet temperatures below about 40° F., such cooling of the air can lead to potentially harmful icing whenever the relative humidity is above about 70%. Accordingly, high performance turbines advantageously have means for heating such cold, moist air. Only about 10 to 15° F. temperature increase is required to reduce the relative humidity from 100% to below 70% when the ambient temperature is 40° F. or lower.
Prior art turbine inlet air heaters have used electric resistance heating, compressor bleed air, steam heating, exhaust heated air, and the like, with attendant capital cost and operating cost.